#include <fstream>
#include <algorithm>
using namespace std;

#define N 1000
#define NM 499500

typedef unsigned long long ull;

ifstream f("trapez.in");
ofstream g("trapez.out");

struct point {
    int x, y;

    bool operator == (const point& a) const {
        return x == a.x && y == a.y;
    }
};

point v[N], m[NM];

//   a.y     b.y
//   ---  <  ---
//   a.x     b.x
bool cmp(point a, point b) {
    return (ull)a.y * b.x < (ull)a.x * b.y;
}

// gcd cannot be 0
point slope(point a, point b) {
    int dy = b.y - a.y;
    int dx = b.x - a.x;
    int gcd = __gcd(dx, dy);
    return {dx / gcd, dy / gcd};
}

int main() {
    int n, idx = 0;
    f >> n;
    for (int i = 0; i < n; i++) {
        f >> v[i].x >> v[i].y;
        for (int j = 0; j < i; j++)
            m[idx++] = slope(v[i], v[j]);
    }
    sort(m, m + idx, cmp);
    
    int s = 0, cnt = 1;
    for (int i = 0 ; i < idx; i++)
        if (m[i] == m[i + 1])
            cnt++;
        else {
            s += cnt * (cnt - 1);
            cnt = 1;
        }

    g << (s >> 1);
    return 0;
}